Many devices utilize mercury in their operation, particularly in the field of electric lamps and lighting. Such devices include arc discharge lamps which typically employ mercury as one of the vaporizable components therein. See, for example, Waymouth, Electric Discharge Lamps, MIT Press 1971 for a description of the basic operating principles of such lamps.
In U.S. Pat. No. 4,379,252, (the '252 patent) the advantages of utilizing higher than normal levels of .sup.196 Hg in the Hg added to fluorescent lamps are described and include unexpectedly high efficiency gains in light output. The disclosure of this patent is hereby incorporated herein by reference.
The drawback of using this isotope lies in its high cost. For example, using conventional enrichment techniques, mercury which has been enhanced to contain about 35% of the .sup.196 Hg isotope can cost about $500 per milligram. While only sub-milligram quantities of this isotope need by added to an incandescent lamp to afford beneficial results, economic realities always play a part in consumer products. Accordingly, it is easy to understand why more economical methods of obtaining this isotope continue to be sought.
Previously Hg entrainment methods used in the photochemical isotope separation of .sup.196 Hg employed a bubbler or sparger system filled with mercury. See for example, Webster and Zare, J. Phys. Chem., 85: 1302 (1981) and FIG. 1. This method has been found to have several disadvantages, particularly at mercury flow rates of 1 g/hr. or higher. The upstream pressure would vary during the bubbling and cause height reduction of the mercury column in the bubbler. Mechanical motion of small droplets necessitated an extended transition of vacuum tubing between the reactor and the bubbler. Given the extended transition region, control of the vapor pressure of mercury is difficult.
The following additional documents are recited as general background information with respect to the subject matter of the present invention. To the extent deemed necessary by artisans of ordinary skill in the art to which this invention pertains, the teachings of these documents are hereby incorporated herein by reference.
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